This Project is based on the hypothesis that HIV-1-induced neurotoxins increase oxidative stress in neurons and this in turn leads to neuronal dysfunction and ultimately death that causes HIV-1 associated dementia. The investigators propose to evaluate novel pharmacologic strategies to decrease oxidative stress and thereby ameliorate neuronal death, using in vitro and in vivo models for HIV-1 associated neurotoxicity. the following aims are proposed: (1) In vitro models of oxidative stress in primary human neuronal cultures exposed to HIV-1-induced neurotoxins. Human fetal neuronal cultures exposed to fixed doses of candidate neurotoxins (Tat, TNF-alpha, PAF, AA, and glutamate) from activated HIV-1-infected macrophages for various times will be evaluated for intracellular glutathione (GSH) concentrations, reactive oxidative intermediates (R01s), and lipid peroxidation. The relative contribution of each neurotoxin to changes in GSH concentrations, R01s and lipid peroxidation will be determined by adding increasing doses of each neurotoxin to neuronal cultures and correlating changes with neuronal cell death. (2) In vitro studies of primary human neuronal cultures exposed to candidate neurotoxins and rescued by neuroprotective strategies. GSH levels, R01s, lipid peroxidation products, and neuronal cell death will be measured at over time after exposure to Tat, TNF-alpha, PAF, AA (or, where appropriate, glutamate) and treated with: a) antioxidant drugs, b) glutamate receptor antagonists, c) monoclonal antibody to TNF-alpha, recombinant PAF acetylhydrolase, or PAF receptor antagonists, or d) herpes viral vectors expressing the anti-apoptosis genes Bcl-2 or BAG-1. (3) In vivo studies exogenous neurotoxins and neuronal apoptosis: To confirm the pathophysiologic relevance of studies in Specific Aim 2, HIV-1-infected macrophages will be cultured with human neuronal aggregates and inoculated into the anterior chamber of SCID mice. Neuronal death will be measured at serial intervals in xenografts treated after engraftment with agents listed in Specific Aim 2 that demonstrate efficacy in reducing neuronal oxidant stress.